js 监听浏览器切换标签栏 之 更改标题

mounted() {
    // js监听浏览器切换标签栏事件
    var OriginTitile = document.title, titleTime
    document.addEventListener("visibilitychange", function() {
      console.log(document.visibilityState); //标签页的状态 visible hidden
      
      if (document.visibilityState === ‘hidden‘) {
        document.title = "(┬＿┬)";
        clearTimeout(titleTime);
      } else {
        document.title = "欢迎回来~";
        titleTime = setTimeout(function() {
          document.title = OriginTitile;
        }, 1500);
      }
    });
  },